Department of Biochemistry and Molecular Biology, The Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, 3010 Victoria, Australia.
J Proteomics. 2013 Oct 8;91:97-105. doi: 10.1016/j.jprot.2013.07.007. Epub 2013 Jul 19.
The venom of marine cone snails is a rich source of pharmacotherapeutic compounds with striking target specificity and functional diversity. Small, disulfide-rich peptide toxins are the most well characterized active compounds in cone snail venom. However, reports on the presence of larger polypeptides have recently emerged. The majority of these studies have focused on the content of the dissected venom gland rather than the injected venom itself. Recent breakthroughs in the sensitivity of protein and nucleotide sequencing techniques allow for the exploration of the proteomic diversity of injected venom. Using mass spectrometric analysis of injected venoms of the two fish-hunting cone snails Conus purpurascens and Conus ermineus, we demonstrate the presence of angiotensin-converting enzyme-1 (ACE-1) and endothelin converting enzyme-1 (ECE-1), metalloproteases that activate potent vasoconstrictive peptides. ACE activity was confirmed in the venom of C. purpurascens and was significantly reduced in venom preincubated with the ACE inhibitor captopril. Reverse-transcription PCR demonstrated that these enzymes are expressed in the venom glands of other cone snail species with different prey preferences. These findings strongly suggest that cone snails employ compounds that cause disruption of cardiovascular function as part of their complex envenomation strategy, leading to the enhancement of neurotropic peptide toxin activity.
To our knowledge, this is the first study to show the presence of ACE and ECE in the venom of cone snails. Identification of these vasoactive peptide-releasing proteases in the injected venoms of two fish-hunting cone snails highlights their role in envenomation and enhances our understanding of the complex hunting strategies utilized by these marine predators. Our findings on the expression of these enzymes in other cone snail species suggests an important biological role of ACE and ECE in these animals and points towards recruitment into venom from general physiological processes.
海洋锥形蜗牛的毒液是药理学化合物的丰富来源，具有显著的靶标特异性和功能多样性。小的、富含二硫键的肽毒素是在锥形蜗牛毒液中最具特征的活性化合物。然而，最近有关于存在更大多肽的报道。这些研究大多数集中在解剖的毒液腺中的含量上，而不是注射的毒液本身。最近在蛋白质和核苷酸测序技术的灵敏度方面的突破允许探索注射毒液的蛋白质组多样性。使用两种猎鱼锥形蜗牛 Conus purpurascens 和 Conus ermineus 的注射毒液的质谱分析，我们证明了血管紧张素转换酶-1 (ACE-1) 和内皮素转换酶-1 (ECE-1) 的存在，这些酶是激活强效血管收缩肽的金属蛋白酶。在 C. purpurascens 的毒液中证实了 ACE 活性，并且在用 ACE 抑制剂卡托普利预孵育的毒液中显著降低。逆转录 PCR 表明这些酶在具有不同猎物偏好的其他锥形蜗牛物种的毒液腺中表达。这些发现强烈表明，锥形蜗牛将导致心血管功能紊乱的化合物作为其复杂毒液策略的一部分，从而增强神经毒素活性。
据我们所知，这是第一项表明 ACE 和 ECE 存在于锥形蜗牛毒液中的研究。在两种猎鱼锥形蜗牛的注射毒液中鉴定出这些血管活性肽释放蛋白酶，突出了它们在毒液中的作用，并增强了我们对这些海洋捕食者所利用的复杂狩猎策略的理解。我们在其他锥形蜗牛物种中发现这些酶的表达表明 ACE 和 ECE 在这些动物中的重要生物学作用，并指出从一般生理过程中招募到毒液中。
